Pediatric Hypertrophic Pyloric Stenosis Surgery Treatment & Management

Although medical treatment (see Medical Therapy) has been used to manage pyloric stenosis, pyloromyotomy has been firmly established as the treatment of choice for this condition. Adequate preoperative resuscitation is essential. Fluid resuscitation is guided by adequate urine output (1 mL/kg/hr) and by normalization of acid-base disturbances and electrolyte and bicarbonate levels.

Outcome studies comparing open and laparoscopic approaches to pyloromyotomy are becoming more numerous overall as the trend toward more minimally invasive procedures is becoming more important to the public. ^[26] In one survey, cosmetic outcome was valued highly enough that as many as 88% of parents were willing to pay additional expenses for their children to have smaller scars. ^[35]

With a higher public demand for minimally invasive surgery, it is important to keep abreast of trends in surgical resident training. Cosper et al reported that 93% of surgeons agreed that residents need to perform at least four open pyloromyotomies in order to become competent in the procedure; however, 44% reported that their residents performed fewer than four, a finding explained partly by the increased use of a laparoscopic approach and partly by decreased opportunities for residents in the operating room (OR) to acquire the necessary skills. ^[36]

In one study, the rate of complications associated with laparoscopic pyloromyotomy when a general surgery resident participates was 5.4-fold higher than that associated with performance by a pediatric resident, despite close attending supervision. ^[37] However, because more surgical residents are specializing, as well as because there may be fewer general surgeons who are comfortable performing pyloromyotomies, patients with pyloric stenosis may eventually experience a healthcare access problem. The need for parents to travel longer distances to a larger center that offers (or performs a high volume) of this procedure may result in further attempts at other modalities for treating pyloric stenosis.

For example, in an alternative approach used to address the pylorus externally, Zhang et al reported nine successful applications of endoscopic pyloromyotomy in resolving infantile hypertrophic pyloric stenosis. ^[38] After transabdominal ultrasonography (US) was used to assess the wall thickness, a 5.9-mm gastroscope was used to create a 2- to 3-mm incision (if the wall was 4-6 mm thick) or a 3- to 4-mm incision (if the wall was >6 mm thick). There were no complications of hemorrhage or perforation; however, one patient developed vomiting after 1 month, which resolved after a repeat procedure. With further research, this may prove to be a safer, more effective, and simpler alternative to the current standard of care.

For more information, see Pediatric Pyloric Stenosis, Pediatric Hypertrophic Pyloric Stenosis, and Imaging in Hypertrophic Pyloric Stenosis.

The primacy of pyloromyotomy in the management of pyloric stenosis notwithstanding, medical management of this condition remains important. Early assessment and treatment of fluid, electrolyte, and acid-base disturbances are paramount. Urgent resuscitation, rather than emergency surgical intervention, is the rule. Once the diagnosis is made, fluid resuscitation is begun. Clinical and biochemical assessments are made and repeated to guide appropriate fluid repletion.

Nonsurgical management was described originally in Europe, using a low-curd feeding of dextrose or breast milk; however, this treatment reportedly took months to complete and was associated with significant morbidity. Reports from Sweden showed that intravenous (IV) nutrition alone also usually failed. Additionally, a biochemical approach using atropine or scopolamine was followed to compensate for the lack of nitric oxide (NO) synthase (NOS) in the pylorus, which is thought to cause the hypertrophy. These anticholinergics were thought to decrease pyloric contractions; however, early success was lacking, and for some time, this approach was thought to be only of historical interest.

In a Japanese study from 1996, Nagita et al reported successfully treating 21 of 23 infants (91%) with pyloric stenosis by using IV atropine, administered at a dosage of 0.04-0.11 mg/kg/day until vomiting ceased, followed by oral atropine for 2 weeks. ^[39]

A subsequent Japanese study, by Kawahara et al in 2005, reported a success rate of 87% in 52 patients treated with IV and oral atropine. ^[40] Manometric studies were used to find the level of atropine that decreased tonic and phasic contractions in the pylorus. The dosing regimen of atropine was 0.01 mg/kg IV six times a day before feedings (median time, 1 wk), followed by 0.02 mg/kg orally after vomiting stopped and infants could tolerate formula in the amount of 150 mL/kg (median time, 44 d).

Hospital stays in this study ranged from 6 to 36 days (median, 13 d); however, despite the longer hospital stay, the costs for the medical group were similar to those for the surgical group, without the inherent risks of general anesthesia and surgery. ^[40] Regarding general outcomes, the two groups showed no difference in weight at age 1 year. Medical treatment for pyloric stenosis could prove useful to patients without sufficient access to surgical care or when surgery would be too risky. The authors concluded that this medical treatment of pyloric stenosis is an effective alternative to pyloromyotomy if the length of hospitalization and the necessity of continuing oral atropine are accepted.

Long-term studies have yet to be conducted to address recurrence rates, hospital costs in other countries, and caregiver compliance for atropine-treated patients with pyloric stenosis. In the United States, the Ramstedt pyloromyotomy remains the optimal treatment for pyloric stenosis.

Preparation for surgery

As noted (see Medical Therapy), pyloric stenosis is not a surgical emergency. The preoperative medical management of patients with pyloric stenosis is paramount for safe general anesthesia. Once the diagnosis is made, fluid resuscitation is begun to treat dehydration and electrolyte and acid-base disturbances. Clinical and biochemical assessments are made and repeated to guide appropriate fluid repletion.

IV therapy consists of 5% dextrose in one-half isotonic sodium chloride solution (0.45% NaCl/D5W) at 1.5 times the maintenance rate. Although children with severe dehydration should receive deficit fluid therapy with isotonic sodium chloride solution (20 mL/kg) initially, ongoing resuscitation should be performed with 0.45% NaCl/D5W to prevent rapid changes in volume and electrolyte levels, which can result in seizures. When urine output has been demonstrated, potassium chloride (10-20 mEq/L) can be added to the fluids.

As a general guideline, infants are deemed adequately resuscitated for the OR once the following criteria are met:

• Good urine output has been demonstrated
• Serum Cl ^– >100 mEq/dL
• Serum HCO ₃ ^– < 30 mEq/dL

In some patients with severe volume abnormalities (>20%) and electrolyte abnormalities (Cl^–< 80 mEq/dL; HCO₃^– >35 mEq/dL; Na⁺< 120 mEq/L), resuscitation may take 48-72 hours. With serum bicarbonate levels exceeding 30 mEq/dL, the potential exists for myocardial dysfunction and respiratory depression. Patients should therefore be monitored for signs of apnea; if such signs are present, they may need to be intubated and mechanically ventilated until surgery is performed.

An alternative preoperative stabilization approach has been proposed for severely alkalemic patients to decrease the preoperative hospital stay. In a report of 16 infants with a pH exceeding 7.60, four patients received standard resuscitation for 4 days and then cimetidine at 10 mg/kg, and 12 received IV cimetidine on admission until the pH dropped below 7.50. ^[41] In all 16, pH reached the goal the same day cimetidine therapy was initiated, and all underwent pyloromyotomy that day. No complications associated with cimetidine were reported. This type of prompt preoperative resuscitation may help shorten hospital stays and reduce overall costs in infants with severe metabolic alkalosis. ^[42]

Operative details

Once the diagnosis of pyloric stenosis has been confirmed, adequate ongoing preoperative fluid resuscitation must be maintained by establishing adequate urine output (1 mL/kg/hr) and correcting acid-base disorders and electrolyte abnormalities. Regarding anesthetic induction for infants with pyloric stenosis, tracheal intubation with muscle paralysis seems to be superior to awake intubation, in that the former reduces the risk of desaturation and bradycardia due to multiple attempts at intubation.

Pyloromyotomy may be performed either as an open procedure, via a right-upper-quadrant (RUQ) horizontal incision or an umbilical incision (Tan-Bianchi operation), or as a laparoscopic procedure ^[2] (see the images below).

Open pyloromyotomy

In 1986, a Tan-Bianchi approach was described in which a pyloromyotomy was performed through a supraumbilical incision that afforded superior cosmesis. ^[43] In 2004, Blumer et al compared the umbilical approach with the RUQ approach in 237 patients and found that the umbilical approach took 3.1 minutes longer (28.5 vs 31.6 min); however, this difference was clinically irrelevant, in that there were no significant differences with respect to length of hospital stay, mucosal perforations, or wound infections. ^[44] The umbilical approach also was considered to provide a superior cosmetic outcome.

In 2004, Alberti et al reported modifying the Tan-Bianchi approach with a right semicircular umbilical incision, thus keeping all the incisions in the same axis, allowing for delivery of a larger pylorus, and decreasing the amount of retractor strain on the wound. ^[45] This approach resulted in a lower rate of hematoma formation and lower wound infection rates (0%) than supraumbilical incisions (16%), despite the use of prophylactic antibiotics with the semicircular umbilical approach.

In this modified Tan-Bianchi operation, after the pyloric channel is delivered from the abdomen, a seromuscular incision is made along the anterior border of the hypertrophied pylorus from 1-2 mm proximal to the duodenum to the distal antrum just proximal to the pylorus. ^[45] Great care must be taken not to incise or perforate the underlying mucosa. An alternative superficial V-shaped extension can be made at the duodenal end of the myotomy to reduce the risk of duodenal mucosal injury.

Other variations of the open abdominal approach include a technique reported by Yokomori et al in 2006, who used a semicircumumbilical incision to create a 1.5-cm sliding window with an 8-cm subcutaneous space. ^[46] This space was then slid 3-4 cm toward the RUQ. The abdomen was entered and the pyloromyotomy performed intracorporeally within the window. This type of incision can afford an uneventful postoperative course, along with a good cosmetic outcome.

One study compared an umbilical approach using a transverse muscle cutting incision and a vertical linea alba incision and found no difference in terms of postoperative morbidity. ^[47] In addition, a double-Y or Alalayet pyloromyotomy may be superior to the Ramstedt technique in decreasing postoperative vomiting and increasing weight gain in the first week following surgery.

Another consideration with pyloromyotomy may be the presence of foveolar cell hyperplasia (FCH), ^[48] a type of redundant mucosa, which may be evident on US in 12% of infantile hypertrophic pyloric stenosis cases. In patients diagnosed with FCH, an extended pyloromyotomy may decrease postoperative vomiting and reduce the need for gastric foveolar fold excision due to persistent postoperative vomiting.

Laparoscopic pyloromyotomy

A laparoscopic pyloromyotomy follows the same principles as an open procedure. First described by Alain et al in 1991, ^[49] the laparoscopic approach has been demonstrated as a safe alternative to exteriorizing the pylorus and improving cosmetic results.

The authors' approach entails creating a 5-mm camera port at the umbilicus. A 3-mm atraumatic locking grasping instrument is inserted in the RUQ through a transabdominal stab incision over the duodenum. The grasping instrument is used to stabilize the pyloric channel.

A 3-mm incision is made in the midepigastrium/left upper quadrant (LUQ), over the pyloric olive, through which a sheathed arthrotome is passed (without a trocar). Alternatively, a Bovie electrocautery with an extended tip can be used to create the pyloromyotomy. The pylorus is incised in the same fashion as with the open procedure. The hypertrophied muscle is then bluntly split with a laparoscopic Tanner pyloric spreader. (See the images below.)

Robotic-assisted pyloromyotomy

A robotic pyloromyotomy follows the same steps as the laparoscopic procedure. Whereas robotic pyloromyotomy has the advantages of not exteriorizing the pylorus and of improving cosmetic results, it also helps the surgeon with respect to dexterity, ergonomics, and precision. 

Partin in 1995 and Okada in 1998 described the use of robotic assistance for surgery in children in the form of a camera holder. ^[50]

Hollands in 2002 helped standardize robotic pediatric surgery by overcoming the technical challenges of using robotic surgical telemanipulators to facilitate operation in confined spaces. ^[51] She used the Zeus Robotic Surgical System (Computer Motion, Goleta, CA) on piglets to develop robotic approaches to enteroenterostomy, hepaticojejunostomy, and esophagoesophagostomy. Hollands in 2004 also presented the first data on robotic pyloromyotomy in human infants. ^[52]  

The robotic approach has been demonstrated to be a safe and noninferior alternative to laparoscopic surgery in pediatric patients. Since the initial studies, many other robotic platforms have been used in pediatric surgery to perform multiple complex procedures, including pyloromyotomy. ^[50]

Crystalloid resuscitation is continued postoperatively until the patient returns to full feeding. Data suggest that infants with pyloric stenosis have an increased incidence of postoperative apnea and bradycardia. These infants should be placed on an apnea and cardiac monitor for 24 hours following the operation.

A decrease in the number of hospital days after operation depends to a certain degree on how rapidly feeding is started and advanced. In a 2002 study, Michalsky et al reported that having a clinical pathway decreased surgeon variability by advancing the diet to oral feedings within 5 hours after operation. ^[53] Additionally, the length of hospital stay was significantly reduced (41.8 ± 9.7 vs 57.8 ± 11.7 hr), as were hospital costs ($4555 ± $464 vs $5400 ± $1017).

In a contrasting 2002 study, Puapong et al showed that feeding ad libitum after the patient is awake resulted in a significantly faster return to full-strength feeding than a controlled feeding regimen (29.1 vs 5.1 hr), along with a shorter hospital stay (38.8 ± 16.6 vs 25.1 ± 10.9 d) and a significant decrease in cost per patient ($3560 vs $2290). ^[54] Both studies found that early initiation of feeding led to better recovery and to cost savings.

The author has found the following seven-step feeding regimen to be safe and adequate:

1. Give the patient nothing by mouth (NPO) for 6 hours in the recovery room
2. Then, on demand, give 15 mL of Pedialyte every 2-3 hours for two feedings
3. If 15 mL is tolerated, advance to 30 mL of Pedialyte every 2-3 hours for two feedings
4. If 30 mL is tolerated, advance to 30 mL of full-strength formula every 2-3 hours for two feedings
5. If full-strength formula is tolerated, advance to spontaneous feedings
6. If vomiting occurs, repeat the step at which vomiting occurs and advance when tolerated
7. If the patient is being breastfed and the mother has bottled milk, follow the above schedule

If the patient is being breastfed and no bottled milk is available, follow the schedule below:

• Follow steps 1, 2, and 3 above
• Have the patient breastfeed on each side for 5 minutes every 2 hours for two feedings
• Have the patient breastfeed on each side for 10 minutes every 2 hours for two feedings
• Have the patient breastfeed spontaneously

Slow feeding and gentle burping help prevent wet burps postoperatively. Intermittent vomiting persisting through the first postoperative week is sometimes observed in patients with a protracted course of emesis and severe dehydration preoperatively. Vomiting lasting longer than 7 days postoperatively should alert the physician to the possibility of an incomplete pyloromyotomy. An upper gastrointestinal (UGI) study may be obtained but is useful only for demonstrating gastroesophageal reflux; the radiographic appearances of pyloric stenosis may persist for several months following complete pyloromyotomy.

Although pyloromyotomy is safe and curative and can be performed virtually without operative mortality (< 0.5%) and morbidity (< 10%), it is not without potential complications. Potential intraoperative and postoperative complications include the following:

• Bleeding
• Perforation 
• Wound infection

Duodenal or gastric perforation, the most serious complication, rarely occurs; however, if it goes unrecognized before wound closure, devastating or lethal consequences are possible. The infant with an enteric leak develops pain, distention, fever, and peritonitis. Ongoing fluid requirements, generalized sepsis, vascular collapse, and death follow if the enteric leak is not recognized and treated. Suspected perforation postoperatively requires immediate reexploration. Recognition of this complication at the time of surgery is important.

Mucosal perforation most commonly results from extending the myotomy beyond the pyloric-duodenal junction. If perforation occurs, the mucosal defect should be repaired and the myotomy completed. An omental patch may be sutured to the perforation site, and a paraduodenal drain may be considered. If any question exists about the success of the closure, a UGI study can be obtained before feedings are initiated. The patient should continue to receive antibiotics until feedings are resumed.

Bleeding is a rare complication of pyloromyotomy. Other complications that are more common but less serious include the following:

• Superficial wound infections (usually Staphylococcus aureus)
• Postoperative vomiting

Patients with wound erythema, drainage, or both undergo wound opening and debridement and antibiotic therapy. Incomplete myotomy results in ongoing gastric outlet obstruction and requires reoperation. However, ongoing emesis after pyloromyotomy does not mean an incomplete myotomy was performed. Patients with prolonged preoperative obstruction develop gastric distention and dysmotility, which may cause postoperative emesis for up to 1 week after an adequate pyloromyotomy. Oral atropine has been suggested as a viable treatment for persistent emesis after pyloromyotomy. ^[55]

The follow-up care regimen involves a routine postoperative visit at 1 week to check wounds and to ensure that the patient is once again gaining weight.